Latest news with #theory
WIRED
18-07-2025
- Science
- WIRED
Einstein Showed That Time Is Relative. But … Why Is It?
Jul 18, 2025 7:00 AM The mind-bending concept of time dilation results from a seemingly harmless assumption—that the speed of light is the same for all observers. Video:So, you're driving a car at half the speed of light. (Both hands on the wheel, please.) You turn on the headlights. How fast would you see this light traveling? What about a person standing by the road? Would they see the light beam moving at 1.5 times the speed of light? But that's impossible, right? Nothing is faster than light. Yes, it seems tricky. The problem is, our ideas about the world are based on our experiences, and we don't have much experience going that fast. I mean, the speed of light is 3 x 108 meters per second, a number we represent with the letter c. That's 670 million miles per hour, friend, and things start to get weird at extreme speeds. Illustration: Rhett Allain It turns out that both the driver and the person on the road would measure the light as traveling at the same speed, c. The motion of the light source (the car) and the relative motion of the observers make no difference. Albert Einstein predicted this in 1905, and it's one of the two main postulates behind his theory of special relativity. Oh, it doesn't sound so 'special' to you? Well, what he then showed is that if the speed of light is a universal constant, then time is relative . The faster you move through space, the slower you move through time. The clock on a hyper-speed spaceship would literally tick slower, and if you were in that ship, you would age more slowly than your friends back home. That's called time dilation. A Commonsense Example The idea that everyone sees light traveling at the same speed seems like common sense. But let's look at a more familiar situation, and you'll see that it's not how things usually work. Say you're driving at 10 meters per second, and someone in the car takes a tennis ball and throws it forward with a speed of 20 m/s. A bystander who happens to have a radar gun measures the speed of the ball. What reading do they get ? Illustration: Rhett Allain Nope, NOT 20 m/s. To them the ball is moving at 30 m/s (i.e., 10 + 20). So much for common sense. The difference arises from the fact that they are measuring from different 'reference frames,' one moving, the other stationary. It's all good, though; everyone agrees on the outcome. If the ball hits the person, the miscreants and the bystander would calculate the same time of impact. Yes, the people in the car see the ball moving at a slower speed, but they also see the bystander moving toward them (from their perspective), so it works out the same in the end. This is the other main postulate of special relativity: The physics are the same for all reference frames—or to be specific, for all 'inertial,' or non-accelerating, frames. Observers can be moving at different velocities, but those velocities have to be constant. Anyway, now maybe you can see why it's actually quite bizarre that the speed of light is the same for all observers, regardless of their motion. Waves in an Empty Sea How did Einstein get this crazy idea ? I'm going to show you two reasons. The first is that light is an electromagnetic wave. Physicists had long known that light behaved like a wave. But waves need a medium to 'wave' in. Ocean waves require water; sound waves require air. Remove the medium and there is no wave. But then, what medium was sunlight passing through as it traveled through space? In the 1800s, many physicists believed there must be a medium in space, and they called it the luminiferous aether because that's fun to say. In 1887, Albert Michelson and Edward Morley devised a clever experiment to detect this aether. They built a device called an interferometer, which split a beam of light in half and sent the halves along two paths of equal length, bouncing off mirrors, and merging again at a detector, like this: Illustration: Rhett Allain Obviously they didn't have a laser, but they had a similar light source. Now, if the Earth was moving through an aether as it circled the sun, that aether would change the speed of light, depending on whether the light was moving in the direction of Earth's motion or at a right angle to that motion. And here's the genius part: They didn't have to actually measure the speed of light, they only had to see if the two beams arrived at the detector at the same time. If there was any change in speed, the beams would be out of sync and would cancel each other when recombined. That interference would show up as a dark spot on the detector. If they moved at exactly the same speed, the sinusoidal waves would align and you'd see a bright spot. They ran this experiment at all different times of year to get different angles with respect to the sun, but the result was always the same. There was no change in speed—which meant, sadly, that people had to stop saying 'luminiferous aether.' Evidently, light waves could travel through a vacuum! Maxwell's Equations and Reference Frames The reason for this, as proven by Heinrich Hertz, is that light is an electromagnetic wave—an oscillation of electric and magnetic fields perpendicular to each other. The changing electric field creates a magnetic field, and the changing magnetic field creates an electric field, and this endless cycle makes light self-propagating. It can travel through empty space because it's two waves in one. Now for the rough part (mathematically). We know the relationship between the electric and magnetic fields—it's described in Maxwell's famous four equations. If you use some math stuff (full details here), it's possible to write the following equations for the electric field (E) and the magnetic field (B). (If all these Greek symbols are Greek to you, just skip over this.) All you need to know is that, together, these equations describe an electromagnetic wave. But wait! That's not all. If we plug in the values of μ 0 and ε 0 —the fundamental magnetic and electric constants, respectively—you get a wave speed (v for velocity) that is exactly the speed of light: Einstein used this to postulate that the speed of light was the same for all observers. How? Well, since we accepted that any one inertial reference frame is as valid as another, Maxwell's equations must work in both. That means the speed of light is the same in both reference frames—even if they're in motion relative to one another. UNLIKE the tennis ball scenario above! Time Dilation Finally, imagine we build a clock to measure time. Not one of your grandfather's clocks with a swinging pendulum, which would be a problem in zero gravity. Our clock is cooler than that. Basically we get two parallel mirrors and bounce a pulse of light back and forth between them. Illustration: Rhett Allain If we know the distance between the mirrors (s) and the speed of the light (we do, it's c), then we can calculate the time for one tick. Now assume our clock is in a spaceship with a big window, like in the movies. This spaceship is moving with a constant velocity that is half the speed of light (c/2) with respect to some nearby planet. Someone on that planet uses a telescope to look through the spaceship window and peek at the light clock. Here's what that planet person would see: Illustration: Rhett Allain Notice that since the spaceship is moving, the light has to travel at an angle in order to hit the other spot on the opposite mirror. If we continued this, it would be a series of zigzags. Take a minute to think about that. It's like if you were riding in a bus and tossed a ball straight up and then caught it without moving your hand. In your reference frame, the ball just moves straight up and down. But to that guy on the street, the ball would trace out an arc, moving up and down but also forward. In our light clock, since the light has to travel at an angle to hit the correct spot, it travels a farther distance . Oh, but that light still travels at the speed of light, so it takes more time to reach the other mirror. And if the spaceship is moving at a speed of c/2, that would be a lot more time. Result? As seen from the person on the planet, the spaceship clock ticks slower. There you have it: time dilation. Does this mean that time goes slower for the people on the spaceship? Nope. In their reference frame the light just bounces up and down and time is normal. Yes, it seems very weird, but it's not. It only seems weird because we never travel anywhere near the speed of light. In fact, time slows down in any moving vehicle—even when you get in your car and drive to work—but at normal speeds the effect is so tiny that it's imperceptible.
Arab News
15-07-2025
- Science
- Arab News
What We Are Reading Today: ‘In The Brain, In Theory'
Author: ROMAIN BRETTE 'In The Brain, In Theory,' Romain Brette argues that the brain is not a 'biological computer' because living organisms are not engineered. Engineering is the use of knowledge to solve technical problems, to build an artifact with a plan. Brette reviews the main theoretical frameworks for thinking about the brain, including computation, neural representations, information, and prediction, and finds them poorly suited to the study of biological cognition. He proposes understanding the brain as a self-organized, developing community of living entities rather than an optimized assembly of machine components.
Yahoo
01-07-2025
- Science
- Yahoo
3D Time Could Solve Physics' Biggest Problem, Says Bizarre New Study
Clocks might be far more fundamental to physics than we ever realized. A new theory suggests what we see around us – from the smallest of quantum actions to the cosmic crawl of entire galaxies – could all be literally a matter of time. Three dimensions of time, in fact. The basic idea of 3D time isn't new. But University of Alaska geophysicist Gunther Kletetschka says his mathematical framework is the first to reproduce known properties of the Universe, making it a somewhat serious contender for uniting physics under one consistent model. "Earlier 3D time proposals were primarily mathematical constructs without these concrete experimental connections," says Kletetschka. Related: "My work transforms the concept from an interesting mathematical possibility into a physically testable theory with multiple independent verification channels." Something is wrong with our current models of reality. While quantum mechanics and general relativity both explain our Universe to a degree that's uncannily accurate, each emerges from fundamentally distinct grounds – one granular and random, the other seamless and immutable. These irreconcilable starting points make it a challenge to construct a single, all-ruling theory of physics that explains gravity in the same way as it does the other three forces. Not that theorists haven't tried. Kletetschka proposes a complete rethink on the basics, pulling back the fabric of space-time itself to come up with a new bedrock to base reality on. While we use the word time to describe virtually any series of events, there's a clear contrast in scale that extends from the near-instantaneous flitting of quantum particles to the eons of cosmic growth stretching into eternity. On the cosmic end, time can be relative, distorting in relation to mass and acceleration. Up close, time is undecided, equally capable of looking to the past as it does to the future. And drifting in the middle is an existence as boringly predictable as tomorrow's sunrise. Separating these scales into their own dimensions provides us with three paths to follow, each marching to its own beat at right angles to the others. By embedding these timelines in mathematics that preserves cause and effect, it's possible to link all three dimensions in a way that could explain everything from how fundamental particles pop up in quantum fields, to why we can't experience quantum weirdness, to the expanding boundaries of the Universe itself. "These three time dimensions are the primary fabric of everything, like the canvas of a painting," says Kletetschka. "Space still exists with its three dimensions, but it's more like the paint on the canvas rather than the canvas itself." Related: Importantly, the framework precisely reproduces known masses of a number of particles, such as top quarks, muons, and electrons, and volunteers predictions for the unknown masses of neutrinos and subtle influences on the speeds of gravitational waves. That means the theory could receive support from future experiments, and potentially contribute to a more united approach to physics as a whole. "The path to unification might require fundamentally reconsidering the nature of physical reality itself," says Kletetschka. This research was published in Reports in Advances of Physical Sciences. Physicists Catch Light in 'Imaginary Time' in Scientific First Not All Uranium Can Be Used in Weapons. Here's What 'Enrichment' Means. Scientists Caught Sperm Defying One of Newton's Laws of Physics
Yahoo
28-06-2025
- Science
- Yahoo
Time Is Three-Dimensional and Space Is Just a Side Effect, Scientist Says
A fringe new theory suggests that time is the fundamental structure of the physical universe, and space is merely a byproduct. According to Gunther Kletetschka, a geologist — not a physicist, you'll note, but more on that later — from the University of Alaska Fairbanks, time is three-dimensional and the dimensions of space are an emergent property of it, a press release from the university explains. "These three time dimensions are the primary fabric of everything, like the canvas of a painting," Kletetschka said in the blurb. "Space still exists with its three dimensions, but it's more like the paint on the canvas rather than the canvas itself." Three-dimensional time is a theory that has been proposed before, though generally in pretty inaccessible terms. Similarly to the explanation for three dimensions of space — length, width, and depth — 3D time theory claims that time can move forward in the linear progression we know, sideways between parallel possible timelines, and along each one of those as it unfolds. Yes, it's a pretty mind-blowing concept — but scientists have long theorized that time, as the fourth dimension in Albert Einstein's theory of relativity, is less intuitive than it seems in everyday reality. While other 3D time theories rely on traditional physics, Kletetschka suggests that his may help explain the many outstanding questions accepted physics still harbors. In a somewhat grandiose manner, the geologist even claims that his 3D time proposal could operate as a grand unifying theory or "theory of everything," the Holy Grail of quantum mechanics that would explain how the universe works on a sweeping level. "The path to unification might require fundamentally reconsidering the nature of physical reality itself," the scientist said. "This theory demonstrates how viewing time as three-dimensional can naturally resolve multiple physics puzzles through a single coherent mathematical framework." Obviously, there are an astonishing number of caveats to consider here. For one, Kletetschka is not a theoretical physicist — he's a geologist, and according to his university bio he also has some experience in astronomy. Extraordinary claims all call for extraordinary evidence. And the claims here are already stirring controversy: as an editor's note added to the end of the press release cautions, the scientist's theory was published in the journal Reports in Advances of Physical Sciences, a "legitimate step," but one that isn't remotely sufficient to take it out of the realm of the fringe. That journal, the note adds, is "relatively low-impact and niche, and its peer review does not match the rigorous scrutiny applied by top-tier journals." "The theory is still in the early stages of scrutiny," the note concluded, "and has not been published in leading physics journals or independently verified through experiments or peer-reviewed replication." Still, it's a fascinating concept to consider — especially because we still don't know exactly how time works, anyway. More on fringe theories: Physicists Say We Were Completely Wrong About How Gravity Works
Sustainability Times
11-06-2025
- Science
- Sustainability Times
'Einstein Would Lose His Mind': Scientists Uncover Ultimate Power Limit That Could Finally Fuse Relativity with Quantum Mechanics
IN A NUTSHELL 🔬 Researchers propose that dividing spacetime into tiny, discrete units could link general relativity and quantum mechanics . into tiny, discrete units could link and . 💡 New study suggests that gravity , a macroscopic force, might be explained using quantum theory in extreme conditions like black holes. , a macroscopic force, might be explained using in extreme conditions like black holes. 🔗 The concept of Planck power introduces an upper limit to energy release, challenging the notion of infinite energy levels. introduces an upper limit to energy release, challenging the notion of infinite energy levels. 🌌 This research could revolutionize our understanding of the universe, offering new insights and technological advancements. In recent years, the quest to unify the fundamental forces of the universe has taken a significant leap forward. Scientists are inching closer to bridging the gap between two of the most revolutionary theories in physics: general relativity and quantum mechanics. A new study suggests that by dividing spacetime into minuscule units, we might find a way to explain gravity—a macroscopic force—via the principles of quantum theory. This could potentially resolve the long-standing conundrum of how these two seemingly incompatible frameworks can coexist in extreme conditions like those found in black holes or the initial moments of the Big Bang. Energy Always Has an Upper Limit In the realm of physics, the idea that energy can be released at infinitely high levels has long posed challenges, particularly when dealing with quantum gravity. Picture a universe where space and time are not continuous but consist of minute, indivisible building blocks. This concept is akin to pixels on a digital screen or quanta in quantum mechanics, where energy and momentum are not smooth but come in discrete packets. In such a framework, objects would not move continuously but in fixed steps, and time would progress in tiny, discrete increments. These increments are so minute that they escape notice in our everyday lives. According to the principles of general relativity, gravity arises from the curvature of spacetime. If spacetime itself is fragmented, this curvature must also adhere to a quantized, step-like pattern. Moreover, if spacetime is quantized, then the energy release must have an upper limit, much like how no object can exceed the speed of light. This theoretical upper limit, known as Planck power, is unimaginably large—around 10⁵³ watts—but nonetheless finite. Wolfgang Wieland, the study's author, suggests that this concept could allow us to break down gravitational waves into their smallest quanta. 'Einstein Was Wrong': These Groundbreaking Black Hole Models Shatter Century-Old Theories with Unbelievable New Insights A Part of the Ongoing Quest Since the early 20th century, the relationship between general relativity and quantum mechanics has puzzled scientists. Initially thought to be mutually exclusive, recent research has indicated potential pathways to unite these theories, especially when examining phenomena like black holes. Previous studies have employed Einstein's field equations and entropy to explore how macroscopic phenomena such as gravity and spacetime can be described using quantum mechanics. While this current study isn't the first to attempt this unification, it is groundbreaking in its use of Planck power as a basis for exploring the connection. Despite these advancements, the theories remain largely theoretical, confined to mathematical equations and assumptions. Further research is needed to experimentally validate these ideas and potentially revolutionize our understanding of the universe. 'I Watched Time Slow Down in Orbit': This ESA Clock Is Revolutionizing the Science of Space-Time Precision The Implications of Quantized Spacetime If the concept of quantized spacetime proves accurate, it could fundamentally alter our understanding of the cosmos. This idea suggests that spacetime is not a smooth fabric but a collection of discrete units, changing the way we perceive gravity and other fundamental forces. In this model, the universe would operate much like a digital simulation, with everything broken down into its smallest components. Such a shift could have profound implications for fields ranging from cosmology to particle physics. The understanding of quantized spacetime could lead to new insights into how the universe began and how it might evolve. It could also provide a new lens through which to examine the fundamental forces that govern the cosmos. As researchers continue to explore this concept, it's possible that new technologies and methodologies will emerge, enabling us to probe deeper into the universe's mysteries. 'Earth Is Being Poisoned From Below': Microplastics Found in Earthworms Threaten Crops, Food Chains, and Human Survival Future Directions in Unified Physics The pursuit of a unified theory that encapsulates both general relativity and quantum mechanics remains one of the most compelling challenges in modern physics. The idea of quantized spacetime is a critical step in this journey, offering a new framework for understanding the universe. As scientists continue to explore this avenue, they are likely to encounter new challenges and opportunities for discovery. This ongoing research could pave the way for advances in technology and deepen our understanding of the universe's fundamental laws. The implications of such a breakthrough would not only transform physics but also potentially impact other scientific disciplines and even everyday life. As we stand on the brink of this new frontier, one can't help but wonder: what other secrets does the universe hold, waiting to be uncovered? Our author used artificial intelligence to enhance this article. Did you like it? 4.6/5 (25)
